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WASHINGTON (CNN) -- Pentagon sources say some of the most incriminating evidence against Marines under investigation in the deaths of civilians at Haditha is a set of photographs taken by another group of Marines who came along afterward and helped clean up the scene.

CNN is the first news organization to examine those images. They were snapped before an aspiring Iraq journalist videotaped the aftermath of the November 19 deaths. That video convinced Time magazine to pursue the story earlier this year.

Pentagon sources say the 30 images of men, women and children are some of the strongest evidence that, in some cases, the victims were shot inside their homes and at close range -- not killed by shrapnel from a roadside bomb or by stray bullets from a distant firefight, as Marines had claimed. (Watch what the new images show about the civilian deaths -- 2:51)

Senior Pentagon officials have said a probe into the November deaths tends to support allegations that Marines carried out an unprovoked massacre after one of their comrades was killed by a roadside bomb. The military is investigating both the deaths and a possible cover-up.

The Marines originally reported that Lance Cpl. Miguel Terrazas and 15 Iraqi civilians were killed by a roadside bomb in Haditha, a town on the Euphrates River in northwestern Iraq that was the scene of heavy fighting in 2005. They later added that eight insurgents were killed in an ensuing gun battle.

The Marine photographs are evidence in a criminal probe, and only investigators and a few very senior officials have access to them.

"I have seen the photographs, but they are part of the investigation and I'm not going to talk about those photographs," Marine commandant Gen. Michael Hagee told reporters Wednesday.

But a source allowed CNN to examine copies of the photographs, which a military official said match in both number and description the pictures in the possession of investigators.

The source would not allow CNN to have copies of the images out of concern over personal repercussions.

There are images of 24 bodies, each marked with red numbers. Some of numbers are written on foreheads, others on the victim's backs. A senior military official told CNN that in some cases the numbers may denote the location of bullet wounds.

Among the images:

A woman and child leaning against the wall, heads slumped forward.

Another woman and child shot in bed.

A man sprawled face down with his legs behind him.

An elderly woman slumped over, her neck possibly snapped by the force of gunfire.

All of the victims were wearing casual attire. Some had been shot in the head. Some were face down, others face up.

The pictures appear to show the locations of the bodies in the houses before a Marine unit loaded them into a truck and brought them to a morgue.

Pentagon officials said there are no plans to release the gruesome images, even after the criminal investigation is complete.

The Haditha photos, like the images of detainee abuse at Abu Ghraib prison, would incite anti-American fervor and therefore constitute a threat to national security, they said.

In a separate incident, seven Marines and a Navy medical corpsman are being held in a brig at Camp Pendleton, California, to face possible murder charges in connection with the April killing of an Iraqi man in Hamandiya, a military officer with direct knowledge of the investigation said.

Briefing reporters Wednesday, Hagee was tight-lipped about the investigations but said Marines "absolutely know right from wrong."

Hagee flew to Iraq two weeks ago on a trip the Marine Corps said was already scheduled. But he used the time to lecture his Marines on what he called "the American way of war" amid the two probes.

Hagee said he is "gravely concerned" by the allegations and promised that the investigations now under way will be thorough and complete.

The U.S. command in Baghdad ordered an investigation into the Haditha killings in February, after Time magazine reporters presented video of the scene to American commanders.